SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '819d461582974f0a1b97068e2709c7f8f8aae52618e8938e0dfc5a9e3f90d19b' 
  AND token = 'G4Cl6znpvzWkZwXEfL9+tWQHmcHiP/uXY/vdi3Ggdnc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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