SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5122e76bd8f03a1b365c945d2a589b0af2f86ef2afc6462f0230c969f749451' 
  AND token = '+ofgau3hiWqMVdbB2W/Un14/B1VrhDvcKYlQW6nwBf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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