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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e520413aea234dc5533a7fea86d1afb8cc114300b262e1d6c84bd38d69e23fbf' 
  AND token = 'op7EEZZQ6+zZ8pm/Li4bv5ifAKT5XwlwL1ffMNF/Xo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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