SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '310c7403e58830f72aaf5aba05b5000f507fd79833ed834c9f743d6ae126623c' 
  AND token = 'lIDEbHWrrCVGhBPXAZq3YFQMBV471gCRcGC+1uohXDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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