SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6763cf2674c336336fc30515bfa4f1a2da1ee148c9baf1ebeb6ba320ed645e7' 
  AND token = 'WSsTzzToBDfTu/RLGpDtl4XS+ChLYUkD7mle/WjXejQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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