SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b513ed8475d13ffa2ed3042235efd45cbbcc414a37ba620d9070ac40193c5450' 
  AND token = 'keAiUL1zngdLxbvPLO91DhDOsL5eR0P2ZWRkODQURhs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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