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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8e50aafa724bf8e142f91ca1eed015f0ba5e4218b70b66f4284d9fe6e2fd1ad' 
  AND token = 'PGhuZqNd5SeYBtKgjungv9jdrgk5rqTE50CuZnQvcPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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