SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cf136f86b3a3cfd8801bc6b47f03759b83376db9188ee95ccb13bdc315c9a58' 
  AND token = 'HeUTqiILjsCEzLFxzt6hZgqYqu7IfG3DcOGTRad7Qqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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