SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78de5e3da70fa88a5d98b0e1231e3070885b2da72607e37197085979f0ed5c57' 
  AND token = 'gAJlWe85q9i7dHmkZFdLvRH3eMcmbqum5Vul/M5Ss+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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