SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18f1eeca37b749ffc8e3b421490c82b0ea18b460d9862d5986a92d5e48d343f2' 
  AND token = 'gXZlx7QUFxFGGEJ8pCWR3ogDyWJK9z2gL+C5Pq3NiMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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