SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e75c18668825c918eee7e3ccfd0e610c985224051c6a2b0816f57eceec6dfed5' 
  AND token = 'rggq2f9D/etQ1jW4ATPenBXWVJfNsQ6KJqaCe4FDObo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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