SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2dde466236f05bfb3b05bc131477a8dc21a3121f43beea25307c6cdae243932e' 
  AND token = 'b1vsTM6jM1zDPnxj43/WVHzOXrUEOBS5DoJVxvV2I+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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