SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c8b333c927b7c8579c93752e24a5235a4a97302a0c1baba59d67c7b05745223' 
  AND token = '+sjXHFS3t5u8yKEWUSfq6uSk/ebVV9QAJa/EnPeXGVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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