SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98edd9f40df9002d2ae1d7bfd9f12ee800dac9a362b43fcd7977d1f26ccaad23' 
  AND token = 'JSyHni93tnIQWnJQTtKdFQUkLRChu+gijMZIaaB3rlQ=' 
  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"
    }
  }
}