SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30cdd7cc33d03811c55e399b22b130aee441154e937da857c7df986117979ffa' 
  AND token = '34xKStJDb2jvYAM32HBzwrf6oFNH13q3Z8rEogZyaRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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