SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e27ddef73d60b86eb5ae38a085af11d593d25def4138664957488ea2d5e5c8a6' 
  AND token = 'mXPgtzffhyGRrvagqRFnExLbmfPWdGiBEnQ8YQeLg7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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