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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8ef6e0f06f6f5dfa0da22135d479fb90c6781dbfc2554a92e75db3b697b1b1f' 
  AND token = 'bmuDO+SeumVfQfSTWibsaVmMVcTjNc5wBDH5Eha7/mI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}