SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71abab2409fbd379dd2ac4dbe27c395d5c65483cc9d3e9ef945decf0f05788fc' 
  AND token = 'TscCaFnwGk6+vwYtjwCDnQ0UNDfWJyBe4PsSiTlkqa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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