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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '554cf8b8bd50818ca43719fcc1f5fbe98e2e912c4e025e714f0dfa849043fb71' 
  AND token = '6QcsdzrRJRNesw1N2RB09FzAMEp5h8tc7DHQDnDWVGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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