SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52c51d163d32da74ebe324f185ddaaa2d6c513a85ee4ac72c2c0d7e2c4d3608e' 
  AND token = 'xy/ZCHrTHKqXuvH9XorgfeLy0s35hlDKciz7xnVyc0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}