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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7c62db7b3cfa64f33da9725af1439402419130d57fef077ec97c190439233df' 
  AND token = 'l9XYIL6tbu6G7TdbE+/on8EgZm9ztoxauIRtnZHxNMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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