SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '876b201a88c5a93fabea1a3bec256a67d577aacd98bc1a3a766f8c54c14686eb' 
  AND token = '9k08K1Hv0Ldf64hDbEQMA7Fqw89qPbf5On43mXiR1bk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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