SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a500596ae89fbf7f09bd9f5cf8d662fb4c4240eb6d72a26d74a96903546f664' 
  AND token = 'fzYGDtASpsjv8m1qcWKx4JzYlcDFnedIeJPdO5ZV/WM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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