SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f266f15ac1a2575d1c6b912406336c7483bb4c2f68691247cf2602c6804c982b' 
  AND token = 'xhIl9+CugrgpzvTm9hCUgB/bPg/IfTjYXbUqxMoeOjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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