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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b676f1551ba7017a01f723a8310e4ad91f837ed1f5d42c61c091033a96496e63' 
  AND token = '0JAjAWRKW5HNIZLmsvOIE67qaoVbD2RVtRSeN0LeBbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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