SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df853baded0bcd7e09f695f3e726c5da62ff1acd7442123d92a9e96e4e638fa6' 
  AND token = 'MHFzulkV1rE1/dFbApV1kDkNduR4WwCNjle90TWRF1A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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