SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3322e3f9dc8dbc30659b334206c6b75bb60330aa771be564ff984cd76756c34' 
  AND token = 'gL1sQPMdJnnKEELKtwiLF0jXcYllXFXwHcGJmY+lMHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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