SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84cf0e9e6a5f5e27839f8a44599530fb3b69e855218875364c5e4d1ce125aba1' 
  AND token = 'nTLOwY6Jvx1/XGPlviFgpATG29Mp6LrsxUYUpVJIGco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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