SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51f92225398575b50aa6f086f9433b9f7f51749d59447cdb5c60d5f3ed65fc68' 
  AND token = 'w4gt9NBgsX1SUOZ15jUp72h4VhZF/NKKCTZniwNAdOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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