SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b858e1dce311dadf827343a7703c95e2da548849cd9593d1357fd0ee4646de4' 
  AND token = 'SRSUAACEoZyrJuzTBarZRd7Y5H6nTY5RNywuXS1clRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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