SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da5fc77ab948f36119277ed281da58b6ade9ac4c50daa45706982664b1bc8d19' 
  AND token = 'MYIXlygnYWX5vzd0JAJ1mOrOaw8G1QBq0+szAv3+6iQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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