SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b00806c5b121794c72aa3f56bf11c8ba25a645c84955106d19016ac372a768f0' 
  AND token = 'zkxb0yKZiC0RkQ+nG4bB8wXWj/AS31/lXHn7HZTNqlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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