SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f80c719c68d0b067596875443dbf18253f3e8e7fb274976b871863da86d2de49' 
  AND token = 'U/vNsWJNqun8xY5mAqbSzovFMianrxX3102fYwhG7Y0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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