SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '620a8f239778449b601f580eed61d42f9b6471bca37efdfb02db84c548efe2f1' 
  AND token = 'GiIBcDhtRH4ftFXhYeiVXxsG46O97AnBEbsiFGCMFX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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