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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b16eadc9cd96b658faee1fed7279da992dd3e87d85fd32d97a65fe1d9eca8290' 
  AND token = 'GRGc4Dj9NZD7mdYYf8lzLGIt0JBoxe3+qh1NoLKmdCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}