SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c26b196d80eccf62c238438b800fc19d4fb5915375dd905d6d271eb00e1a57c1' 
  AND token = 'mG6gN6of4RjvjNPD3mZwsnZuYF9zTHyswkHhWBKywhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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