SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1503e55ca2a134cff2a8ae3feb32ee760732f057139cbe35f8a62b3da15601b9' 
  AND token = 'uXukStXAQHHyrWo3o/EUJb3+xtQul2LPmPteq46AvKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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