SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20716d1e86178168e42809e480d0246ccdad92766da4381ed5f215f05232523d' 
  AND token = 'V9T8+WYIg+JI2CzabfYZV+5c5vLYw1MixQV8cZWMGhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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