SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a324a6fbf2f9ae31e2e2a0cfa5101cd58746f6fc815e5a68a86619e1ba4a34f2' 
  AND token = 'DG8Rzuv4JVAZmEUNI4nkHprKBj86t0LP5wU8qRZIhm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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