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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3c6bdff327608c3ea3d3d7182492020a69829925e38f64bdd8d18bd3eb48536' 
  AND token = 'eYKSWhGNjOsCzauB10ewYw89+ntkRvsDhfj9fX7GNF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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