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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c2e234f93efe1a636b279ca2c9f1d6471278e86e34c1ddb6a5c6135333f6bdc2' 
  AND token = 'bOxyUxRlaWtb//WcHhOgVJ6S4qRmhl5ixnSr6c8i6As=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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