SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7709bf28000c44d416179a7cd31d8be1e1fb533f6f25fe22d2fe435b4817d21' 
  AND token = 'YihHdgGzEwYC0FHCYA+ouBwFC+S2/nTBWf9azXMSU54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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