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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd39ad58287aea86552087b6af8c4bdcd64a87e728e6e705bbffeb03c0cf7bcd4' 
  AND token = '0P23Ie5eKMpA+zMI/JSNx72aYXfSbBhBA2xPS+ZtQxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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