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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f567f785c335e0b6808ebe1128da394cafeb77aa6dd382a45216b10d981e1bb' 
  AND token = 't4Xehjdada4cVIBADaUrNwld0ZBGUhprWIWtQSVQeK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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