SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '814b1b4ae3d01da2e459e076afb14281342930e8fdce7dba27799eb48ab19320' 
  AND token = 'r3JQEs4bDzsZgxL2oBGPQ+avAMXnj3VWiioeJxss9Vs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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