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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3e88480422ca622f283b56678ec16a9d46e1cd88b38f40d9286d5f9c0effc7d' 
  AND token = 'j+EPEgM6r1hCvG4QzaG5bk86ahfhM0W9+ccYahRDpSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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