SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51e19c418f9169b5f84f380db8c03de61bf0a491f2710c29980452539241246b' 
  AND token = 'Q2RmOV26JLmQRPPt3AwV85XgOPciVhQ1U1IvddbOnSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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