SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc5b3185eb80578b0b9820d14c6454baee0aabe2d72f4f755d74c70940f1c5e3' 
  AND token = 'gEqNZx1Kog00qKfak37k/eWKhbUUfaRkihmoDrVFrsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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