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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e12ba8c02b84b8a95e0ed5cb843b7d1e8918d8d1b96e2547ca6e79453eb0b997' 
  AND token = 'DXSI9l49rKlVh0myrD/70s7tcQdiDqKEwMmMAUz+V6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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