SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7c3a163f97cb9dfd9e440016d39872cc07e838a831065618c7f268ee78941b1' 
  AND token = 'PHX4jz2As015I/BP24kf62tpFvey2GzWBL270QrBccQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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