SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '356e85c72aa929e700041f0208899615040e0ff3929617f435f4498e50465614' 
  AND token = 'FTjJB6rUqBHd9RGAtVbCzTu1BhFWi2z/Ly8Y46Ngq1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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