SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42805b89a09833ff8a0f11b68a052f64e1c833ded362e07f3a4dc8a0df1fa274' 
  AND token = 'fgtSI0Efw0yNaXUU44tyki0dNF+OFqoS0oLViqzl6Mk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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