SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b77a8691badc36d526cff3d800689cdce439023d3ebe04fa58b1587e195286ea' 
  AND token = 'Ye2tde4bMVb0/mgsJu9A5mpH5UIY3jlF+pybFHCEgLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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