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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6b31f86b8fa0eb33762889ea97abea289fde155186c919905d3a55202ed489c4' 
  AND token = '/xpzxwNf3V9Xv5eiKyQKZ1tsaBSkiNcE43VLC2m98vE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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