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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1855a4c967202f025ab6a9a5b7d0ab5c76552bf4029d2b6864863559faad4e1a' 
  AND token = 'WVkTmJ2Zl7PxoHtkVGk6Fg+Hdgl9hag+QH6BpPidqlM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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