SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c987175e5965c22b9372edf3335d38fa73ba9b31759083a67c8e21eaa39064af' 
  AND token = 'FcwM+kPrFACWZXui4puPXz1XCGwqvla4BxNjaMVJSiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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